org.eclipse.persistence.annotations.BatchFetch Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of eclipselink Show documentation

EclipseLink build based upon Git transaction f2b9fc5

There is a newer version: 5.0.0-B03

/*
 * Copyright (c) 2011, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     James Sutherland - initial implementation
package org.eclipse.persistence.annotations;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * A BatchFetch annotation can be used on any relationship mapping,
 * (OneToOne, ManyToOne, OneToMany, ManyToMany, ElementCollection, BasicCollection, BasicMap).
 * It allows the related objects to be batch read in a single query.
 * Batch fetching can also be set at the query level, and it is
 * normally recommended to do so as all queries may not require batching.
 *
 * @author James Sutherland
 * @since EclipseLink 2.1
 */
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface BatchFetch {
    /**
     * (Optional) The type of batch-fetch to use.
     * Either JOIN, EXISTS or IN.
     * JOIN is the default.
     */
    BatchFetchType value() default BatchFetchType.JOIN;

    /**
     * Define the default batch fetch size.
     * This is only used for IN type batch reading and defines
     * the number of keys used in each IN clause.
     * The default size is 256, or the query's pageSize for cursor queries.
     */
    int size() default -1;
}